Sandcast Engine Casings

Think they are supposed to be stronger - metallurgically...

 

It is just lower volume manufacturing option - can't see that they would be any difference. It's a sand mould apposed to a die cast mould.
The fork bottoms on my prototype 999 fork lowers are lost wax cast (which is even more costly and lower volume - and does show any split lines at all due to the wax being melted away to form the mould cavity)

 

they ARE stronger. A mould is made, literally from sand, which is broken to get the resulting cases out. It's an expensive process, but results in a better product. There were a few production cases that were produced with sand casting, but most were cast from traditional moulds. The race cases were usually sandcast and can be reused after their KM/hours limits are reached. I've got a few broken production cases lying round, but no broken sandcast ones.

 

My understanding is that sand casting is used for small production runs where the cost of making moulds and tooling for conventional casting methods is prohibitive.
So it would be used by development/race departments for special parts.
Hence it is often associated with higher spec components but I suspect that the metallurgical properties may even be lower than for "normal" castings.
On the other hand, pressure casting methods use alloys specifically selected for their "castability", often containing high levels of zinc, if memory serves.
This gives better flow into the nether regions of the mould but at the expense of the strength of the finished item.
So, as usual, the answer is probably not very straightforward, but depends on the nitty gritty of the particular situation.
And, in case you're wondering, I speak as an engineer but my experience of casting processes goes little further than what I remember from 1970s student days.